Pulse amplifier



Jan. 28, 1947. w. w. MOE 2,414,968

PULSE AMPLIFIER Filed Nov. 2,. 1942 UTILIZATION DEV/CE GENE/M701? 1 A Fig.2.

Fig. 3.

Inventor-1 William W. Moe,

H His Attorneg.

Patented Jan. 28, 1947 PULSE AMPLIFIER William W. Moe, Stratford, Conn., assignor to General Electric Company, a

New York corporation of Application November 2, 1942, Serial No. 464.303

1 Claim. 1

My invention relates to thermionic amplifying apparatus and particularly to such apparatus which is adapted for the amplification of pulses of electrical energy which are produced at high frequencies.

It is an object of my invention to provide a pulse amplifying or transmitting apparatus including an improved arrangement for introducing a time delay between the impressing of a pulse on the input of the apparatus and the producing of a corresponding pulse at the output thereof.

It is another object of my invention to provide an improved pulse transmitting or amplifying apparatus which shall require a minimum of power for its operation.

The features of my invention which I believe to be novel are set forth with particularity in the appended claim. My invention itself, however, both as to its organization and method of operation, together with further objects and advantages thereof, may best be understood by reference to the following description taken in connection with the accompanying drawing in which Fig. l diagrammatically represents one form of a pulse amplifier embodying my invention and Figs. 2 through are curves representing operating characteristics of my invention.

Briefly, the apparatus shown in Fig. 1 comprises two electron discharge devices connected to provide a two-stage pulse amplifier. The first electron discharge device is arranged to have the pulse or signal to be amplified impressed on its control grid and is provided with an inductance element in its anode circuit. The control electrode is provided with negative bias so that the electron discharge device is normally noncon ducting and when a positive pulse of suflicient magnitude is impressed on the control grid a negative pulse appears across the inductance and energy is stored in the inductance. The anode of the first electron discharge device is coupled through a condenser to the control electrode of the second electron discharge device. The control electrode of the second electron discharge device is also biased so that the device is nonconducting and the negative pulse across the in-- ductance has no effect. However. when the pulse impressed on the first electron discharge'device is terminated, this device becomes nonconducting and the energy is released from the inductance producing .a positive potential on the control electrode of the second device to render it conducting and thereby producing a pulse in the output of the apparatus. The two electron discharge devices are thus so coupled that there is a delay between the time of the impressing of 'a pulse on the input of the apparatus and the producing Of a pulse at its output. Furthermore, both electron discharge devices are normally nonconducting so that power is consumed only during the transmission of a signal.

Referring now to the drawing, in Fig. 1 I have shown a two-stage pulse amplifier or transmitting apparatus comprising a first electron discharge device in and a second electron discharge device II. The device 10 is provided with a control electrode l2 which is biased negatively by some suitable means such as a battery l3 connected to the control electrode through a resistor It. The cathode l5 of the device I0 is connected directly to ground and the anode I6 is connected through an inductance I! to the positive side of a suitable source of direct current indicated as a battery l8.- Suitable apparatus IQ for generating positive pulses of a predetermined frequency is coupled to the control electrode l2 through a condenser 20. Each of the positive pulses impressed upon the control electrode l2 renders the device It! conducting for the duration of the pulse. When current flows in the anode circuit of the device 10, energy is stored in inductance l1 and a negative voltage pulse appears on the anode l8 as indicated at 22 in Fig. 2, the duration of the negative voltage pulse corresponding to the time during which the device I0 is conducting. The anode of the device I0 is coupled to a control electrode 23 of the device ll through a suitable condenser 24. The control electrode 23 is connected through a resistor 25 to a suitable source of negative bias such as a battery 26, the negative bias being suflicient to render the device ll nonconducting. It will, therefore, be apparent that the negative pulse appearing on the anode I6 is impressed on the control electrode 23 but has no effect on. the device ll.

As soon as the device l0 becomes nonconducting at the end of the pulse 22, energy is released from the inductance l1 and a positive voltage pulse appears across the inductance on the plate It as indicated at 21 in Fig. 2. The positive pulse is impressed on the grid 23 through the condenser 24 and overcomes the bias of the grid to render the device ll conducting and produce a pulse a suitable utilization device 30 is connected in the r-anode circuit of the device ll between the anode 11.23 and the ositive side of a source of direct current indicated as a battery 3|. The duration of the pulse at th output of the apparatus de- 3 pends primarily upon the size of the inductance H.

The curve of Fig. 2 has been drawn on the assumption that there was present no capacity tending to cause oscillations upon the release of energy from the inductance I'I. However, there is unavoidably a certain amount of shunt capacity in the inductance which tends to cause the circuit to oscillate through several cycles such indicated in Fig. 3 where I have shown the negative pulse 22 and the positive pulse 21 followed by a small negative pulse 33 and a small positive pulse 3 -3 which positive pulse might cause the device I! to become conducting. In order to prevent the occurrence of a second positive pulse, the condenser 24 may be made of a capacity such that it would be charged by grid or control electrode current flowing in the device H to a negative voltage as indicated at 35 in Fig. 4. The voltage applied to the control electrode 23 is the sum of the voltage of the curves of Figs. 3 and 4.

the apparatus and makes it possible to employ electron discharge devices of smaller capacity. A time delay is provided between the pulse impressed upon the apparatus and that produced at the output of the apparatus. The circuit is therefore particularly adaptable to certain types of signaling systems requiring a time delay. Furthermore, the duration of the output pulse may be different from that of the input pulse according to the size of the inductance and the circuit constants selected.

It is readily apparent from the foregoing that I have provided a simple and effective circuit for amplifying or transmittin pulses with a minimum of power consumption. While I have shown my invention as embodied in a two-stage pulse amplifier, other modifications will readily be apparent to those skilled in the art. For example, any number of stages may be coupled together in the manner illustrated. I do not, therefore, desire my invention to be limited to the particular modification illustrated and described and I intend by the appended claim to cover all modifications within the true spirit and scope of my invention.

What I claim as new and desire to secure by Letters Patent of the United States is:

A pulse transmitting apparatus comprising two electron discharge devices each having a cathode and an anode and a control electrode, means for biasing the control electrode of both of said devices to render said devices normally nonconducting, means for impressing a positive energy pulse on the control electrode of said first device to render said device conducting, an inductance in the anode circuit of said first device for storing energy for the duration of said pulse, a resistance for connecting the control electrode of said second device to ground and a condenser for coupling the anode of said first device and the control electrode of said second device whereby a pulse of positive potential is released by said inductance upon the termination of said first pulse to render said second device conducting and produce a pulse at the output of said apparatus, said inductance having shunt capacitance tending to produce oscillations of energy upon the release of said stored energy and said condenser having its capacity of such value that it is charged by grid current flowing to the control electrode of said second device whereby a negative bias is produced on the control electrode oi? said second device to prevent a second positive pulse due to said oscillations.

WILLIAM W. MOE. 

